Antifouling Activity of Simple Synthetic Diterpenoids against Larvae of the Barnacle Balanus albicostatus Pilsbry

Jun-De Chen,Yi-Ming Lin,Cui-Ling Sun,Dan-Qing Feng,Rui-Zao Yi

doi:10.3390/molecules15118072

Jun-De Chen, Yi-Ming Lin + Show 3 more

Open Access

https://doi.org/10.3390/molecules15118072

Copy DOI

Abstract

Five new pimarane diterpenoids 1-5 were synthesized using ent-8(14)-pimarene-15R,16-diol as starting material. The structures were elucidated by means of extensive NMR and MS analysis. The antifouling activity against larval settlement of the barnacle Balanus albicostatus were evaluated using capsaicin as a positive control. Compounds 1-3 and 5 showed more potent antifouling activity than capsaicin. Compound 5, which exhibited almost the same antifouling activity as starting material, showed better stability than starting material. These compounds all showed antifouling activity in a non-toxic way against larval settlement of the barnacle B. albicostatus. Analysis of structure-activity relationships (SAR) demonstrated that the substituents on the C-15 and C-16 position of pimarane diterpenoid were responsible for the antifouling activity.

Highlights

It is well known that marine fouling organisms often cause technical and economic problems by settling on artificial surfaces submerged in seawaters [1]
Ent-8(14)-pimarene-15R,16-diol was used as starting material due to its potent antifouling activity with EC50 value of 0.04 μg/cm2 [10]
The starting material was treated with methanesulfonyl chloride (MsCl) in pyridine in the presence of NaOH and dimethyl sulfoxide (DMSO) to yield a mixture of compound 4 and the monosubstituted product

Summary

Introduction

It is well known that marine fouling organisms often cause technical and economic problems by settling on artificial surfaces submerged in seawaters [1]. In the course of our investigations on environmentally friendly antifoulants, we observed that pimarane diterpenoids can exhibit non-toxic antifouling activities against larval settlement of the barnacle B. albicostatus [10]. In order to further investigate the effect of free hydroxyl group and substituents on the C-15 and C-16 position of pimarane diterpenoid on the antifouling activity, we used ent-8(14)-pimarene-15R,16-diol as the starting material and synthesized five new pimarane diterpenoids 1-5. These compounds were tested for their antifouling activity against larval settlement of the barnacle Balanus albicostatus, which is an important fouling organism in East Asian coastal waters.

Chemistry

Antifouling Assay

General

Conclusions